I've made it a personal rule as a tank that when I step into duty finder, I will finish whatever dungeon I'm dealt. All the times I've wanted to instantly drop because I'm given something I hate are substantial (I've started referring to DREX as "Antitower Roulette", because that's all I ever get.). But I don't. I only leave when RL stuff happens and I absolutely can't finish the dungeon, and I always feel guilty about it.

I guess that's why I never see bad tanks. Because I'm too self-centred to see my problems.